Aerogels, and in particular silica aerogels, exhibit low density and low thermal conductivity making them useful as insulative materials. Aerogels can be used as insulating materials by themselves or can be combined with other materials such as fibers, adhesives and foams. Aerogels can be formed by removing solvent from hydrogels, such as through supercritical drying techniques or via solvent substitution combined with ambient pressure drying. Silica aerogels are typically hydrophilic but can be rendered hydrophobic through the use of specific treating agents.